Abstract The Chandeleur Submarine Landslide Complex occurs on the upper Mississippi Fan of the Gulf of Mexico in approximately 1100 m of water, 200 km SE of New Orleans, Louisiana. This part of the Mississippi Fan received high sedimentation throughout the Pleistocene, causing high pore fluid pressure and abundant slope failures, though few as large as the Chandeleur. Given its large size, proximity to major coastal cities and seafloor infrastructures, we examine the Chandeleur Slide to understand what led to the initial slope failure and decipher its post-failure transport behaviour using 2D and 3D multichannel seismic surveys, high-resolution bathymetric data, and well logs. We find a large sediment mass with a translational-rotational behaviour that was displaced to the south/SE up to 40 km from the source area. The Chandeleur Slide includes extensional faulting in the headscarp area and compressional structures in the toe where confined by a natural ramp-like structure. Beneath the Chandeleur Slide, we identify a regional sand-rich unit (called the Blue Unit) that is known to be overpressured. Beneath the Blue Unit we observe an upward-migrating salt diapir. We suggest one possible scenario for the origin of the Chandeleur Slide is the combined effects of an upward-migrating salt diapir impinging on an already overpressured Blue Unit, leading to the initial failure. The initial failure was followed by retrogressive headwall retreat northward, which created the prominent scarp on the seafloor. In total, the Chandeleur Slide complex covers an area of about 1000 km 2 and contains about 300 km 3 of sediment.

Abstract Since the last Special Publication on seismic geomorphology, the application of seismic data has grown substantially, revolutionizing our understanding of basin evolution in the process. The papers presented here provide an insight into the direction of travel for seismic geomorphological analyses and how the science has evolved since 2007. New methods of data collection, new methods of processing and visualization, and the integration of new types of complementary data, all have played a role in maximizing the potential palaeo-environmental insights that can be derived from such studies. The submissions range across different geological settings, consisting of glacial, fluvial, volcanic, deltaic and slope settings. Many of these studies integrate different methods, showing what can be achieved by combining multiple datasets to understand the subsurface. As more legacy datasets become available, the observed acceleration in seismic data availability and the associated publications will likely continue. Newer methods and greater knowledge of the subsurface are yielding a greater understanding of not just the palaeoenvironments, but also what generates seismic reflectivity in the subsurface. The study of seismic geomorphology remains in its infancy, and much exciting research potential is yet to be realized.